The present invention relates to lipid-based fillings. More specifically, it relates to lipid-based fillings that have reduced fat and low moisture.
Lipid-based fillings are used to produce a variety of food items. For instance, sandwich cookies and crackers are very popular food items in which lipid-based fillings are used. Typically, two identical biscuits (the shells or basecakes) contain a layer of sweet or savory fat lipid-based filling. There are many variations on this basic type. For example, the shells may be dissimilar in shape or color and one shell may have a hole or holes through which the lipid-based filling can be seen. The sandwich may be formed with wafer sheets and have multiple layers of lipid-based filling between the wafers. Lipid-based filling sandwich biscuits may be enrobed with a chocolate or other coating.
The control of water activity (Aw) in a food product can enable the food product to resist spoilage and maintain a fresh taste and mouthfeel. The water activity of a food, or a food subsystem thereof, is a useful measurement of the degree of xe2x80x9cfreenessxe2x80x9d of water contained in the food. The relatively high water activities that are associated with many lipid-based fillings made by standard formulations permit microbial growth, moisture migration, and other problems to occur in the food product. Fillings with high water activities are, essentially, a medium for supporting microbial growth and, therefore, have limited shelf lives. In addition, fillings with high water activities generally allow water to migrate into the surrounding foodstuff. When the surrounding foodstuff is a material of significantly lower water activity, such as a baked dough, the migration of moisture into the baked dough can make the baked dough xe2x80x9csoggy.xe2x80x9d
In Western countries, there is a general trend away from foods that are high in fat and calories, and decreasing dietary fats has been of special interest since fats have a significantly higher caloric density than either carbohydrates or protein. Hence, consumers have increasingly demanded food products with decreased caloric intake from fats.
Accordingly, it would be desirable to provide lipid-based fillings having reduced fat and low moisture.
The present invention provides reduced-fat, low-moisture lipid-based fillings. The lipid-based fillings can be used in a variety of food products. The low moisture, reduced fat, lipid-based filling comprises at least about 20% non-digestible lipid and other suitable optional ingredients. The filling has a water activity of less than about 0.6 and has at least about 20% less digestible fat than a comparable full-fat lipid-based filling.
In one embodiment, the filling is a cheese filling. The low moisture, reduced fat, lipid-based cheese filling comprises:
(a) from about 20% to about 60% non-digestible lipid;
(b) from about 20% to about 75% dehydrated cheese powder; and
(c) from about 0% to about 55% bulking agent.
Although not as preferred, in an alternate embodiment, the filling comprises at least about 20% lipid, wherein said lipid comprises: (1) from about 20% to about 100% non-digestible lipid; and (2) from about 0% to about 80% digestible lipid. In one alternate embodiment, the filling is a cheese filling comprising:
(a) at least 20% lipid, wherein said lipid comprises:
(1) from about 20% to about 100% non-digestible lipid; and
(2) from about 0% to about 80% digestible lipid;
(b) from about 20% to about 75% dehydrated cheese powder; and
(c) from about 0% to about 55% bulking agent.
The fillings of the present invention can be used with any suitable substrate to form a food product; alternatively the fillings can be used as a stand-alone food item.
A. Definitions
As used herein, xe2x80x9clipid-based fillingxe2x80x9d includes any filling comprising at least about 20% lipid.
As used herein, xe2x80x9creduced fatxe2x80x9d means at least about 20% less digestible fat than a comparable full-fat lipid-based filling.
As used herein, xe2x80x9clow moisturexe2x80x9d means a water activity of less than about 0.6.
As used herein, xe2x80x9cadded lipidxe2x80x9d refers to lipid which is added over and above that amount inherently present in the other ingredients.
As used herein, the term xe2x80x9clipidxe2x80x9d refers to edible fatty substances in a general sense, including natural or synthetic fats and oils consisting essentially of triglycerides, such as, for example soybean oil, corn oil, cottonseed oil, sunflower oil, palm oil, coconut oil, canola oil, fish oil, lard and tallow, which may have been partially or completely hydrogenated or modified otherwise, as well as non-toxic fatty materials having properties similar to triglycerides, herein referred to as non-digestible fats, which materials may be partially or fully indigestible. Reduced calorie fats and edible non-digestible fats, oils or fat substitutes are also included in the term. Mixed triglycerides made from medium and long chain saturated and/or unsaturated fatty acids are also included in the term. See, for example, U.S. Pat. No. 5,288,512 to Seiden. Oils that contain medium chain triglycerides can also be used. See, e.g., U.S. Pat. No. 4,863,753 to Hunter et al. Other oils which may be used include a triacylglycerol oil such as liquid Salatrim(trademark) oil (sold under the trade name Benefat(trademark) III by Cultor Food Science, New York, N.Y.).
The term xe2x80x9cnon-digestible fatxe2x80x9d refers to those edible fatty materials that are partially or totally indigestible, e.g., polyol fatty acid polyesters, such as OLEAN(trademark).
While this invention will be generally described in terms of Olestra, it should be readily apparent that other fat substitutes or mixtures thereof could also be utilized in, and are contemplated by, this invention. Mixtures of fats and fat substitutes are also contemplated herein.
By xe2x80x9cpolyolxe2x80x9d is meant a polyhydric alcohol containing at least 4, preferably from 4 to 11 hydroxyl groups. Polyols include sugars (i.e., monosaccharides, disaccharides, and trisaccharides), sugar alcohols, other sugar derivatives (i.e., alkyl glucosides), polyglycerols such as diglycerol and triglycerol, pentaerythritol, sugar ethers such as sorbitan and polyvinyl alcohols. Specific examples of suitable sugars, sugar alcohols and sugar derivatives include xylose, arabinose, ribose, xylitol, erythritol, glucose, methyl glucoside, mannose, galactose, fructose, sorbitol, maltose, lactose, sucrose, raffinose, and maltotriose.
By xe2x80x9cpolyol fatty acid polyesterxe2x80x9d is meant a polyol having at least 4 fatty acid ester groups. Polyol fatty acid esters that contain 3 or less fatty acid ester groups are generally digested in, and the products of digestion are absorbed from, the intestinal tract much in the manner of ordinary triglyceride fats or oils, whereas those polyol fatty acid esters containing 4 or more fatty acid ester groups are substantially non-digestible and consequently non-absorbable by the human body. It is not necessary that all of the hydroxyl groups of the polyol be esterified, but it is preferable that disaccharide molecules contain no more than 3 unesterified hydroxyl groups for the purpose of being non-digestible. Typically, substantially all, e.g., at least about 85%, of the hydroxyl groups of the polyol are esterified. In the case of sucrose polyesters, typically from about 7 to 8 of the hydroxyl groups of the polyol are esterified.
The polyol fatty acid esters typically contain fatty acid radicals typically having at least 4 carbon atoms and up to 26 carbon atoms. These fatty acid radicals can be derived from naturally occurring or synthetic fatty acids. The fatty acid radicals can be saturated or unsaturated, including positional or geometric isomers, e.g., cis- or trans- isomers, and can be the same for all ester groups, or can be mixtures of different fatty acids.
Liquid non-digestible oils are also included in the term xe2x80x9clipid.xe2x80x9d Liquid non-digestible oils have a complete melting point below about 37xc2x0 C. include liquid polyol fatty acid polyesters (see Jandacek; U.S. Pat. No. 4,005,195; issued Jan. 25, 1977); liquid esters of tricarballylic acids (see Hamm; U.S. Pat. No. 4,508,746; issued Apr. 2, 1985); liquid diesters of dicarboxylic acids such as derivatives of malonic and succinic acid (see Fulcher; U.S. Pat. No. 4,582,927; issued Apr. 15, 1986); liquid triglycerides of alpha-branched chain carboxylic acids (see Whyte; U.S. Pat. No. 3,579,548; issued May 18, 1971); liquid ethers and ether esters containing the neopentyl moiety (see Minich; U.S. Pat. No. 2,962,419; issued Nov. 29, 1960); liquid fatty polyethers of polyglycerol (See Hunter et al; U.S. Pat. No. 3,932,532; issued Jan. 13, 1976); liquid alkyl glycoside fatty acid polyesters (see Meyer et al; U.S. Pat. No. 4,840,815; issued Jun. 20, 1989); liquid polyesters of two ether linked hydroxypolycarboxylic acids (e.g., citric or isocitric acid) (see Huhn et al; U.S. Pat. No. 4,888,195; issued Dec. 19, 1988); various liquid esterfied alkoxylated polyols including liquid esters of epoxide-extended polyols such as liquid esterified propoxylated glycerins (see White et al; U.S. Pat. No. 4,861,613; issued Aug. 29, 1989; Cooper et al; U.S. Pat. No. 5,399,729; issued Mar. 21, 1995; Mazurek; U.S. Pat. No. 5,589,217; issued Dec. 31, 1996; and Mazurek; U.S. Pat. No. 5,597,605; issued Jan. 28, 1997); liquid esterified ethoxylated sugar and sugar alcohol esters (see Ennis et al; U.S. Pat. No. 5,077,073); liquid esterified ethoxylated alkyl glycosides (see Ennis et al; U.S. Pat. No. 5,059,443, issued Oct. 22, 1991); liquid esterified alkoxylated polysaccharides (see Cooper; U.S. Pat. No. 5,273,772; issued Dec. 28, 1993); liquid linked esterified alkoxylated polyols (see Ferenz; U.S. Pat. No. 5,427,815; issued Jun. 27, 1995 and Ferenz et al; U.S. Pat. No. 5,374,446; issued Dec. 20, 1994); liquid esterfied polyoxyalkylene block copolymers (see Cooper; U.S. Pat. No. 5,308,634; issued May 3, 1994); liquid esterified polyethers containing ring-opened oxolane units (see Cooper; U.S. Pat. No. 5,389,392; issued Feb. 14, 1995); liquid alkoxylated polyglycerol polyesters (see Harris; U.S. Pat. No. 5,399,371; issued Mar. 21, 1995); liquid partially esterified polysaccharides (see White; U.S. Pat. No. 4,959,466; issued Sep. 25, 1990); as well as liquid polydimethyl siloxanes (e.g., Fluid Silicones available from Dow Corning). All of the foregoing patents relating to the liquid nondigestible oil component are incorporated herein by reference. Solid non-digestible fats or other solid materials can be added to the liquid non-digestible oils to prevent passive oil loss. Particularly preferred non-digestible fat compositions include those described in U.S. Pat. No. 5,490,995 issued to Corrigan, 1996, U.S. Pat. No. 5,480,667 issued to Corrigan et al, 1996, U.S. Pat. No. 5,451,416 issued to Johnston et al, 1995 and U.S. Pat. No. 5,422,131 issued to Elsen et al, 1995. U.S. Pat. No. 5,419,925 issued to Seiden et al, 1995 describes mixtures of reduced calorie triglycerides and polyol polyesters that can be used herein but provides more digestible fat than is typically preferred.
The preferred non-digestible fats are fatty materials having properties similar to triglycerides such as sucrose polyesters. OLEAN(trademark), a preferred non-digestible fat, is made by The Procter and Gamble Company. These preferred non-digestible fat are described in Young; et al., U.S. Pat. No. 5,085,884, issued Feb. 4, 1992, and U.S. Pat. No. 5,422,131, issued Jun. 6, 1995 to Elsen et al.
All percentages are by weight unless otherwise specified.
B. Lipid-Based Filling
As used herein, xe2x80x9clipid-based fillingxe2x80x9d includes any filling comprising at least about 20% lipid. Preferably, the principal lipid component is a non-digestible fat. The fillings of this invention typically have a lipid component making up from about 20% to about 60% of the total filling composition. The preferred fillings are of a low moisture content to promote shelf stability. The lipid-based fillings have a water activity (Aw) of less than about 0.6.
The inclusion of a sucrose polyester non-digestible fat allows for a reduced fat, reduced calorie product that has improved mouthfeel and flavor versus other lowfat filled biscuits. In comparison, many lowfat filled biscuits use high levels of polyols, emulsifiers, fillers, or moisture to achieve fat reduction. High moisture contributes to microbial growth, and polyols, emulsifiers, and fillers can contribute calories and limit consistency, mouthfeel, and flavor.
Additionally, the filling may comprise additional, optional components.
Optional Ingredients
The filling can contain other suitable ingredients depending upon the flavor or other properties desired. As used herein, xe2x80x9coptional ingredientsxe2x80x9d refers to one or a mixture of more than one of these other suitable ingredients. Non-limiting examples of suitable optional ingredients are set forth below.
The lipid-based fillings of this invention can contain a flavoring and, in most embodiments, at least one other component in addition to the flavoring and the fat components. For example, sandwich cracker fillers typically contain salt. Sandwich cookie fillers typically contain a sweetener; indeed, in sweet creams, the major ingredients are sweetener and fat. The sweetener can be a natural sweetener such as sugar, primarily sucrose, glucose, fructose, and maltose, or any one of known artificial sweeteners including 1-aspartyl-1-phenylalanine methyl ester (commercially available as aspartame or Nutri-Sweet (trademark)), saccharine, cyclamate and the potassium salt of 6-methyl-3,4-dihydro-1,2,3-oxathiazin-4-one-2,2-dioxide (commercially available as acesulfame-K), or a mixture of these.
The filling compositions of the present invention can also contain other ingredients depending upon the flavor or other properties desired. For instance, milk or milk powders or solids (preferably nonfat) can be included, as can eggs, gelatin, cornstarch or other starch such as potato or rice, fruits and nuts, vegetable, cheese and meat pieces, colorings, and lecithin or other emulsifiers. Compositions containing artificial sweeteners substantially sweeter than sucrose typically contain a bulking agent such as polydextrose, isomalt, isomaltulose, polyglucose, polymaltose, carboxymethyl-cellulose, microcrystalline cellulose, cellulose gel, arabinogalactan, as well as mixtures or combinations of any of these. These agents can be included in amounts readily determinable by the skilled artisan.
An emulsifier can be used in the present invention. The emulsifier can be any food compatible emulsifier such as mono- and di-glycerides, lecithin, sucrose monoesters, polyglycerol esters (xe2x80x9cPGExe2x80x9d), sorbitan esters, polyethoxylated glycerols, and mixtures thereof. Typically, up to about 3%, preferably from about 1% to about 3%, stabilizer or emulsifier can be used.
The filling compositions can also optionally comprise flavorants. xe2x80x9cFlavorants,xe2x80x9d as the term is used herein, are agents which contribute to or enhance the flavor of the nut butter. These include sweeteners, flavor enhancers, artificial sweeteners, natural and artificial flavors, flavored or candied bits, nut chunks and other additives which contribute to the flavor of the filling. Sweeteners are selected from the group consisting of sugars, sugar mixtures, artificial sweeteners and other naturally sweet materials. Sugars include, for example, sucrose, fructose, dextrose, honey, molasses, high fructose corn syrup, lactose, maltose, and maltose syrups. Preferably, the sweetener will be something which has a sweetness intensity about that of sucrose or fructose. Sweeteners can be added at a level of about 5% to about 20%, preferably from about 7% to about 12%.
Artificial sweeteners such as aspartame, acesulfam, saccharine, cyclamate, and glycyrrhizin can also be used. The amount of artificial sweetener used should be that amount effective to produce the sweetness that is desired, and would be about the equivalent of the addition of from about 1% to about 7% of sucrose.
Flavor enhancers including salt, or salt substitutes such as potassium chloride, sodium chloride/potassium chloride mixtures, and seasoned salts can also be used. The level of flavor enhancer used is a matter of the desired taste level, but usually is from about 0.1% to about 2%. Other flavorants include natural or artificial flavors, roasted flavors, and praline/caramel flavors, walnut flavors, almond flavors, and flavor compositions.
The present invention can also employ nut chunks and other flavored additives which can be mixed with the filling. These additives include chocolate chips or bits or other flavored bits (e.g., butterscotch and peanuts), jellies (either low calorie jellies or regular jelly or preserves), and praline nuts or other candies. These additives are usually added at a level of from about 1% to about 20% by weight. Nut chunks and flavored bits can contain fats and oils. Thus, the addition of these materials can affect the fat content and the calorie level of the nut spread.
A bulking agent can be included in the cheese filling composition. Bulking agents typically add body or texture to the filling and can be non-nutritive or low calorie materials. Suitable bulking agents include hydrolyzed starch (e.g., corn syrup solids or maltodextrin), dextrose, polydextrose, mono- and disaccharides, starches (e.g., corn, potato, tapioca wheat), as well as mixtures thereof. Corn syrup solids, polydextrose (such as that available from Pfizer Chemicals) and maltodextrin are preferred bulking agents. Sugar substitutes which function like sugars but which are non-nutritive can also be used. Such sugar substitutes include the 5-C-hydroxyalkylaldohexoses described in U.S. Pat. No. 5,041,541, issued Aug. 20, 1991 to Mazur.
The filling can also be fortified with vitamins and/or minerals. These can include, but are not limited to, Vitamin A, Vitamin D, Vitamin K, Vitamin C, Vitamin E, thiamin, riboflavin, niacin, Vitamin B-6, Vitamin B-12, biotin, pantothenic acid, iron, calcium, niacin, magnesium, and mixtures thereof.
Sterols or sterol esters can also be incorporated into the filling of the present invention. Suitable sterol and sterol ester compositions are described in U.S. Pat. No. 3,751,569, issued Aug. 7, 1973 to Erickson; U.S. Pat. No. 5,244,887, issued Sep. 14, 1993 to Straub; U.S. Pat. No. 3,865,939 issued Feb. 11, 1975 to Jandacek et al.; U.S. Pat. No. 3,085,939, issued Apr. 16, 1963 to Wruble; U.S. Pat. No. 5,502,045, issued Mar. 26, 1996 to Miettinen; U.S. Pat. No. 5,958,913, issued Sep. 28, 1999 to Miettinen; and in co-pending PandG Application 8003P, filed Mar. 27, 2000.
C. Cheese Filling
A preferred filling of the present invention is a cheese filling comprising from about 20% to about 60%, preferably from about 25% to about 35%, and most preferably from about 28% to about 33%, non-digestible lipid; and from about 20% to about 75%, preferably from about 40% to about 60%, and most preferably from about 45% to about 55%, dehydrated cheese powder; and from about 0% to about 55%, preferably from about 5% to about 20%, and most preferably from about 10% to about 15% bulking agent.
The preferred cheese filling is reduced in fat and has a low moisture content.
Dehydrated Cheese Powder
Any dehydrated cheese powder suitable for producing an instant cheese, such as those disclosed in U.S. Pat. No. 5,935,633, issued Aug. 10, 1999 to Derian, can be used to make the preferred cheese filling of the present invention. The dehydrated cheese powders generally have less than about 3.5% of moisture.
Dehydrated cheese powders which may be employed in the instant cheese compositions of the present invention include, but are not limited to, Anejo Enchilado Cheese Powder 73870, Monterey Jack Cheese Powder 9497, Mozzarella Zing Cheese Powder 9498, Swiss Zing Cheese Powder 9481, Cotija Cheese Powder 73401, Parmtang Cheese Powder 9335, Romano Tang Cheese Powder 9381, Sharpee for Baking Cheese Powder 9510, Panela Cheese Powder 73397, Hexagon Cheese Powder 9483, Cotija with Jalapeno Cheese Powder 73857 and Cuatro Queso Cheese Powder 73856. Especially preferred is Cheez Zing.
The cheese powders and numbers described above are the commercial names for cheese powders made by Kraft Food Ingredients, a division of Kraft Foods, Inc.
A single dehydrated cheese powder or a mixture of more than one cheese powder may be used as the dehydrated cheese powder in the cheese filling compositions of the present invention.
Bulking Agent
A bulking agent can be included in the cheese filling composition. Bulking agents typically add body or texture to the filling and can be non-nutritive or low calorie materials. Suitable bulking agents include hydrolyzed starch (e.g., corn syrup solids or maltodextrin), dextrose, polydextrose, mono- and disaccharides, starches (e.g., corn, potato, tapioca wheat), as well as mixtures thereof. Corn syrup solids, polydextrose (such as that available from Pfizer Chemicals) and maltodextrin are preferred bulking agents. Sugar substitutes which function like sugars but which are non-nutritive can also be used. Such sugar substitutes include the 5-C-hydroxyalkylaldohexoses described in U.S. Pat. No. 5,041,541, issued Aug. 20, 1991 to Mazur.
The preferred bulking agent is hydrolyzed starch. The preferred hydrolyzed starches include maltodextrins and corn syrup solids. The preferred hydrolyzed starches have Dextrose Equivalent (D.E.) values of from about 5 to about 30, preferably from about 10 to about 20. Maltrin(trademark) M050, M100, M150, M180, M200, and M250 (available from Grain Processing Corporation, Iowa) are preferred maltodextrins. The D.E. value is a measure of the reducing equivalence of the hydrolyzed starch referenced to dextrose and is expressed as a percentage (on a dry basis). The higher the D.E. value, the higher the dextrose equivalence of the starch.
Process for Making Cheese Filling
The dry ingredients are first blended in a suitable mixer, such as a ribbon blender. The non-digestible lipid is melted and then combined with the dry ingredients. Mixing is continued until the lipid is homogeneously blended with the dry ingredients.
D. Substrate
Although the present invention is generally described herein in terms of a lipid-based filling suitable for use in combination with a substrate, it should be understood that the lipid-based filling can also be used as a stand-alone food item. For example, the lipid-based filling can be consumed without being employed as part of another food item. It is fully contemplated that the lipid-based filling can be separately packaged for later consumption or use, such as in a pressurized container, a bowl, a tub, a jar, or any other suitable container. Furthermore, the lipid-based filling can be used for any other appropriate uses such as a topping or a spread. For instance, it can be spread on a cracker or toast points and used as an hors d""oeuvre.
The filling of the present invention can be utilized with any suitable substrate. For example, the fillings of this invention can be employed in a variety of food products, including bakery, dessert, snack, candy, dairy, nut, meat, egg, and vegetable products. The fillings are especially adapted to all types of bakery products including leavened baked products, both yeast raised and chemically leavened, and unleavened baked products. Bakery products include cakes, breads, rolls, pastries, cookies, biscuits, and savory crackers. Other suitable food products include jelly rolls, pirouettes, wafers, and hollow snack foods. For example, the filling of the present invention can be used in snack foods such as tortilla sandwiches or potato crisp sandwiches, comprising two chips which sandwich a filling.
Preferred substrates for use herein include base cakes such as crackers, cookies, and biscuits; these can be used with the filling of the present invention to form sandwich biscuits. (As used herein, the term xe2x80x9csandwich biscuitsxe2x80x9d is broad enough to include sandwich cookies, sandwich crackers, and the like.) Any suitable base cake can be used for making the sandwich biscuits of the present invention. Preferably, the base cake is prepared using non-digestible fat and is low in fat and calories.
The preparation of a preferred sandwich biscuit is described below.
E. Sandwich Biscuit
For sandwich biscuits, the fillings are formulated, mixed, and optionally aerated before applying to the shell or basecake by stencilling, depositing, extruding, or other means known to the skilled artisan. The basecake and filler combination is then capped with another basecake.
Although not as preferred, in an alternate embodiment, the filling comprises at least about 20% lipid, wherein said lipid comprises: (1) from about 20% to about 100% non-digestible lipid; and (2) from about 0% to about 80% digestible lipid. In one embodiment, the filling is a cheese filling comprising:
(a) at least 20% lipid, wherein said lipid comprises:
(1) from about 20% to about 100% non-digestible lipid; and
(2) from about 0% to about 80% digestible lipid;
(b) from about 20% to about 75% dehydrated cheese powder; and
(c) from about 0% to about 55% bulking agent.
Parameters used to characterize elements of the present invention are quantified by particular analytical methods. These methods are described in detail as follows. (All laboratory instruments should be operated according to manufacturers"" instructions, as set forth in the instrument operation manuals and/or other instructional materials, unless otherwise indicated.)
1. Fat Content
The method used to measure total fat content (both digestible and non-digestible) herein is AOAC 935.39 (1997).
Digestible Fat Content
Digestible lipid (NLEA) method AOAC PVM 4:1995 is used to determine the digestible fat content.
Non-Digestible Fat Content
Non-Digestible Fat Content=Total Fat Contentxe2x88x92Digestible Fat Content 
Olestra-Containing Foodsxe2x80x94Digestible Fat and Saturated Fat: The content of total digestible fat and total digestible saturated fat of a food is measured according to the published AOAC peer-verified method for quantifying fat in olestra-containing snack foods (AOAC Peer-Verified Method PVM 4:1995, xe2x80x9cCapillary Gas Chromatographic Determination of Fat in Olestra Savory Snack Productsxe2x80x9d, AOAC International, Gaithersburg, Md.).
2. Moisture Content
The moisture content can be determined by a forced air oven volatiles method as follows:
Equipment:
Forced air oven, aluminum tins with lids, Cabinet-type desiccator
Procedure:
1. Weigh tin and lid to 0.0001 grams and record weight as tare weight
2. Place 2-3 gram ground sample into tin, weigh to 0.0001 grams and record as gross weight
3. Set oven temperature to 105xc2x0 C.
4. Place tin containing the sample in oven for 1 hour, uncovered
5. Remove tin containing the sample from the oven, cover the tin, and place in desiccator until cooled to room temperature
6. Weigh tin, lid and dried sample to 0.0001 grams and record as final dried weight
Calculations
1. Sample weight=gross wt.xe2x88x92tare wt.
2. Final weight=weight recorded in step 6
3. Moisture Content (%)=[(gross wtxe2x88x92final wt.)/sample wt]xc3x97100.
3. Water Activity (Aw)
The water activity is defined as the ratio Aw=p/po where p represents the actual partial pressure of water vapor and po the maximum possible water vapor pressure of pure water (saturation pressure) at the same temperature. The Aw level is therefore dimensionless; pure water has a level of 1.0, and a completely water-free substance has a level of 0.0. The relationship between the equilibrium relative humidity ERH in a food and the water activity is Awxc3x97100=ERH.
Instrument
Conductivity humidity meter Rotronic Hygroskop DT (model WA-40 TH) with an operational temperature range from 0 to 100xc2x0 C., and 0 to 100% RH.
Method
1. Weighxcx9c5 grams of the sample and transfer it into a plastic bag.
2. Break the sample into small pieces with a flat object.
3. The samples to be measured are placed in small polysterene dishes in the bottom half of the measuring station.
4. Maintain the temperature constant by setting the equipment in a constant room temperature, or by using a water bath connected to the cells.
5. Wait until the reading of Aw does not change anymore (reading is stable). A red light from the panel will indicate that the instrument is still reading a decrease or increase in value for Aw.
6. Remove the dish with the sample from the chamber and measure moisture content.